The Yukon government says it found mould in one portable at Porter Creek Secondary School, which was supposed to house a program from the Wood Street Centre this school year.
The portable will be closed for at least two to four weeks, said Jennifer Macgillivray, assistant deputy minister with the Department of Highways and Public Works.
The Yukon Workers' Compensation Health and Safety Board said it investigated two portable classrooms following safety concerns last week.
The Yukon Department of Education says two of the centre's programs, known as CHAOS (Community, Heritage, Adventure, Outdoors and Skills) and FACES (French Achievement Challenge Environment Stewardship) are being temporarily housed in other areas of the school.
Superintendent Paul McFadyen said mould was found in the portable intended to house the CHAOS program. He said the other two portables are usable. Air quality testing began on Thursday following safety concerns, said Wood Street Centre principal Darren Hays in an online update for parents last week.
Macgillivray said they had no concerns when they inspected the three portables at Porter Creek earlier in the summer.
However, she said on Aug. 10 there was water damage due to an open window in a portable that was used previously for storage.
Macgillvray said they found a "small amount of mould" in the exterior wall during repairs. They did air and surface testing, she said, and found mould in one of the surface samples.
Macgillvary said they will "remediate" the mould and will re-test the air afterward. She said the process will take two to four weeks, after which they will decide on the portable's future.
Principal Hays said the Wood Street Centre's health and safety committee had concerns about the portables, which were investigated last Wednesday afternoon. The school was waiting for the results of visual inspections and air quality testing to determine next steps.
He told parents in the online update that results were expected early this week.
"I can assure parents we are prioritizing this investigation," said Andrew Robulack, spokesperson with the Yukon Workers' Compensation Health and Safety Board, said Wednesday.
Hays told CBC News he was not authorized to do an interview.
Robulack said the workers' safety board was working on the safety investigation with the Yukon Department of Education and the Department of Highways and Public Works.
Wood Street Centre programs were relocated to other schools this year as part of Yukon's school reopening plan, spawning opposition from several parents and students.